Rear bumper for an automobile



FIG. 1 is a front perspective view of a rear bumper for an automobile showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right-side view thereof;

FIG. 5 is a left-side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof. 

The ornamental design for a rear bumper for an automobile, as shown and described. 